To achieve good yields and high grain quality, and to avoid increased weed pressure in subsequent crops, weeds must be controlled efficiently in organic cereal production. Different mechanical devices are available for weed control.
The tined harrow and the rotary hoe are two commonly used mechanical tools for weed control. In recent years, the Treffler Company re-invented the concept of the harrow and introduced the precision tined harrow. Inagro tested the tined harrow, the rotary hoe and the precision tined harrow to determine the most effective device.
The precision tined harrow had the best impact on soil and weeds, as each tine leaves its own trace. The rotary hoe just created small holes, but broke up the soil crust. Two successive treatments doubled the efficiency against weeds.
• Weed management in organic farming requires an integrated approach, taking into account rotation, soil, available tools, prevalent weeds, etc.
• The smaller the weeds, the more sensitive they are to mechanical treatment with the harrow. The best results are achieved between the ‘sprout’ and ‘first leaf’ stage of the weeds. However, for mechanical weed management, the crop must be well established. Therefore, between the rising of the crop and the 3-leaves growth stage, mechanical control is not recommended.
• Soil conditions are crucial, especially in case of crust (e.g., after winter). An early harrowing or hoeing, when soil is ‘drying white’, is needed to break up the crust. The rotary hoe has proved to be the most effective tool for this.
• Do not be afraid of damaging your cereal crop from the 3-leaves stage onwards. Cereals are capable of recovering. Adjust speed and drive rather slowly in young crops. The rotary hoe and the precision tine harrow allow earlier treatments than the traditional tined harrow.
• If the results are not sufficient over the years, it is recommended to sow cereals with a row spacing of 30 cm. This allows the combination of hoeing and harrowing for better weed control.
• If you intend to buy a new harrow, inform yourself about the different devices available. Ask colleagues and advisors about their experiences.